1. Field of the Invention
The present invention relates to an ink, an ink set, an ink cartridge, a recording unit, an image recording apparatus and an image recording method.
2. Related Background Art
Hitherto, as a black ink for writing implements such as fountain pen, sign pen or ball-point pen and a black ink for an ink-jet printer, an ink using carbon black, a black colorant, high in optical density of image and excellent in fastness has been proposed. Especially in recent years, a detailed research and development has been made from diverse aspects such as composition and property of the ink, so as to perform a good recording even on plain paper such as copy paper used generally in offices, report paper, notebook paper, letter paper, bond paper and serial slip paper. For example, Japanese Patent Application Laid-Open Nos. 63-152681 and 64-6074 disclose a water-based pigment ink containing carbon black and a dispersant. Besides, Japanese Patent Application Laid-Open No. 8-3498 mentions technical problems that ejection becomes unstable and no sufficient printing density cannot be obtained when an ink containing carbon black together with a dispersant is used as ink for ink-jet printer, and it discloses a water-based pigment ink comprising a self dispersible carbon black using no dispersant as an ink capable of solving such problems.